This invention elates to a liner hanger system wherein a liner is to be suspended within an outer casing in the well bore as the liner is lowered into the outer casing for that purpose. As well known in the art, when the liner is so landed, it is cemented in place by means of cement pumped downwardly through and upwardly through the annulus between the casing, and then packed off within the outer casing.
A typical installation of this type, wherein the liner is suspended with the use of slips, is shown and described in Provisional Application No. 60/292,049, filed May 18, 2001, entitled Liner Hanger System, and assigned to the assignee of the present invention.
Other hangers for this purpose, i.e., hanging an inner casing within an outer casing, have locking elements adapted to be expanded into matching locking grooves formed in the outer casing. In some cases, the locking elements are adapted to be spring biased into matching grooves formed in the outer casing. However, these springs are susceptible to breaking or other malfunctions. This is especially true since the hanger often comprises a large number of intricate parts which are expensive to replace, and which require a delay in the overall well operations. In still other cases, the hangers having only a single latching part for fitting within a single groove, thus limiting its load carrying capacity.
The primary object of this invention is to provide a casing hanger system which overcomes these and other problems inherent in prior hangers for such systems.
These and other objects are accomplished, in accordance with the illustrated embodiment of this invention, by a liner hanger system comprising a joint of casing adapted to be connected as part of an outer casing installed within a wellborn, and a liner adapted to be lowered and landed within the outer casing. The bore of the casing joint has a polished bore and vertically spaced, upwardly facing landing surfaces formed therein, and the liner includes a tubular body having a recess formed about its body, and a hanger element comprising a circumferentially expandible and contractible C-ring disposed within the recess. The ring has teeth on its outer diameter for landing on the landing surfaces of the casing joint when in its expanded portion, and upon relative vertical movement with respect to the liner, is expanded outwardly against the polished bore. Upon continued relative movement of the liner and ring, the teeth will move into a position in which they expand further outwardly into landed positions on the landing surfaces to permit the liner to be suspended therefrom.